| ̷ ̷ ̷ ̷ at iso- +|thalik- noun
Etymology: isophthalic International Scientific Vocabulary is- + phthalic
: a crystalline diacid C 6 H 4 (COOH) 2 isomeric with phthalic acid made usually by oxidation of meta- xylene and used in making synthetic resins and esters for use as plasticizers; meta- benzene-dicarboxylic acid